In the field of communications using an antenna positioned on a carrier and in a confined volume, the technical problems to be resolved are notably the following:                to ensure a continuous and accurate pointing of the antenna towards the satellite,        to allow for a hemispherical pointing without a singular point,        to retain the aim of the antenna towards the satellite by taking into account movements of the carrier, such as the roll, the pitch, the yaw, the gyration effect of the carrier,        to have a maximum antenna travel area in order to be able to retain the aim of the satellite on movements of the carrier with pitch and roll of large amplitude even when the satellite is situated at a lower elevation relative to the carrier,        to be adapted to the levels of vibrations and of mechanical impacts encountered on the mobile carriers,        to be very compact with a minimal external diameter, a reduced height and a low weight,        to have a significant free volume on the rear part of the antenna in order to be able to embed transmission and/or reception radiofrequency RF equipment,        to be simple to produce, to install and to maintain in operation.        
To resolve some of these problems, the prior art describes different positioning systems with 2 or 3 axes.
The patent application US 2002/0030631 describes a positioner with 2 axes, X-Y mount, using a half-ring for the X axis rotation.
The patent U.S. Pat. No. 6198452 discloses a positioner with 3 axes in which the elements ensuring the motor-drive of the 3 axes are superposed relative to one another having a significant bulk heightwise, axes that converge at one and the same point offering an optimized volume of revolution of the antenna, non-orthogonal and coplanar axes exhibiting complex kinematics. Its drawbacks are its significant bulk heightwise and complex kinematics.
The patent application WO 93/05363 describes a positioner with 3 perpendicular axes. The azimuth and elevation axes are perpendicular. The third cross-elevation axis converging with the first two is horizontal and perpendicular to the other two axes. The motor-drive elements of the elevation and cross-elevation axes use mechanical motor/belt/pulley assemblies arranged in the rear part of the antenna. An inclined central foot and a mechanical axis at the rear of the antenna supports the motor-drive elements. In this case, the drawback with this positioner results from the complexity and the bulk of the mechanical motor/belt/pulley motor-drive elements and of the fastening elements situated at the rear of the antenna. Because of this, the space available at the rear of the antenna is not optimized.
The positioners known to the Applicant do not notably resolve the following problems:    a) to have a 3-axis antenna positioner with minimal bulk that has:    b) a kinematic of the movements of the antenna that lies within a cylinder of diameter equal to the diameter of the antenna mounted on the antenna positioner,    c) a reduced positioner system height,    d) an extended antenna pointing area, greater than the half-sphere, to allow for negative pointing,    e) to be able to have maximum free space at the rear of the antenna for placing electronic or RF transmission and/or reception components for example,    f) to obtain a mechanical design and a motor-drive that are simple and compact.